Showing papers on "Electromagnetic coil published in 1979"

Remote position and orientation detection employing magnetic flux linkage

Abstract: The process and system for locating the position and orientation of an implement in space wherein a varying magnetic field responsive component (14) such as a coil is positioned upon the implement. A magnetic field source (12) excitable from an a.c. source derives alternating flux fields which are moved along or parallel to coordinate axes established at a reference plane. The coordinate position of the sensor is derived by determining the positions of minima and maxima flux linkage during magnetic field source movement.

DC-to-DC switching converter with zero input and output current ripple and integrated magnetics circuits

Abstract: An improved dc-to-dc converter is provided comprised of two inductances, an input inductance in series with the input source and an output inductance in series with the load, and between the two inductances, two storage capacitances in series with the two inductances. Switching means alternately connect the junction between the input inductance and the first series capacitance, and the junction between the second capacitance and output inductance, to a junction common to the source and load. A third inductance is connected between the junction of the two capacitances and the return current paths for the source and load. In one of the embodiments of the invention, all three inductances are combined on the same core thus comprising a single magnetic circuit with three windings. In another embodiment of the invention an isolation transformer is first used to replace the third inductance. Again, both input and output inductor and isolation transformer are merged into a single magnetic circuit with four windings. In any of the embodiments of the invention, a zero current ripple can be obtained at both the input and the output simultaneously by a proper design of the magnetic circuit. A new method of integrated magnetics design is then disclosed to improve performance of other converter structures by properly merging their magnetics components.

Multiple Layer Series Connected Winding Design for Minimum Losses

Abstract: The classical one dimensional magnetic field and eddy current distribution ("proximity effect") within a series connected multiple layer coil is reexamined with regard to power losses withinthe windings. When the lengthand number of layers ina coilare fixed, the power dissipation within each layer can be minimized by choosing a specific radial thickness for each layer. Above or below this thickness, the losses within the winding increase. The conductor thickness which results in minimum dissipation depends on the relative position of the layer. When compared to a design having a constant thickness for each layer (chosen for minimum total dissipation), it is found that substantial savings in power consumption can be realized by employing a variable thickness of conductor. The one dimensional solution in cylindrical coordinates for the eddy current and skin effect in amultiple layer series connected coil is alsopresented. By solving the problem n cylindrical coordinates, the effect of curvature on the power consumption within each layer is apparent. This analysis should have application to the design of power transformers, armature windings, and inductors for power transmission lines.

Variable mutual transductance tuned antenna

Abstract: An electromagnetic tuning device for RF circuits and particularly loading coils for antennas is disclosed. The preferred devices have a coil which produces a generally torroidal shaped electromagnetic field that is intensified by either a core of ferromagnetic material or a second coil inside the other coil. An insulating material surrounds and hermetically seals the coil and field intensifying device that is inside said coil; and an electrically conductive tuning ring is positioned outside of the insulating material for producing a counter magnetic field which opposes and cuts down the field produced by the first mentioned coil. In one embodiment, the tuning ring is threaded and it threadably engages the insulating material so it can be adjustably positioned relative to the torroidal field. In another embodiment the tuning ring is connected in electrical series circuit with a variable resistor. In both embodiments the tuning ring is insulated from ground and the coil so that nonproductive current flow is prevented. In a further embodiment, an electrically conductive shield having magnetic field transmitting windows is positioned between the tuning ring and the coil to greatly reduce capacitive effects on the coil by the environment.

Generation of horizontally polarized shear waves in ferromagnetic materials using magnetostrictively coupled meander‐coil electromagnetic transducers

Abstract: A new electromagnetic transducer configuration is described for generating horizontally polarized shear (SH) waves in ferromagnetic materials. The transducer consists of a meander coil and static bias magnetic field parallel to the coil elements. This configuration generates no ultrasonic waves in a nonmagnetic metal since the induced eddy currents are parallel to the bias field and the driving Lorentz forces vanish. However, the configuration provides coupling to SH waves in ferromagnetic materials through magnetostrictive effects. Experimental measurements of the variation of transduction efficiency with bias field in nickel and 4130 steel plate are presented and compared to the efficiency obtained with the same meander coils when the bias is rotated 90° in the plane of the plate so that antisymmetric Lamb waves are generated. Peak efficiencies occur at considerably different bias fields for the two configurations. This result, as well as other features in the data, are interpreted in terms of a simple ...

Eddy current method and apparatus for inspecting ferromagnetic tubular members

Abstract: Casing inspection apparatus and method are disclosed for determining defects and other anomalies in ferromagnetic oil well casing. The inspection apparatus utilizes a pair of coaxial transmitter coils for generating an alternating magnetic field in the casing thereby inducing circumferential currents in the casing wall. These circumferential currents and the magnetic field associated with the currents are perturbed by corrosion, holes, and other anomalies both inside and outside the casing wall. Differential receiver coils are urged in proximity with the casing wall to generate a differential receiver signal in response to such perturbations in the magnetic field. The differential receivers are provided with three coils serially connected and having N, 2N and N winding turns respectively. The windings of the coils are disposed in adjacent relationship to one another and wound in a direction opposite to the adjacent winding. The casing inspection apparatus achieves enhanced sensitivity to small defects and reduced sensitivity to magnetic anomalies by processing both the amplitude and phase components of the receiver signal.

Wind turbine generator system

Abstract: Wind turbine generator systems incorporating a multi-speed pole amplitude modulated type dynamo electric machine allowing efficient operation at consecutive speeds in a ratio preferably less than 2:1. A current limiting reactor, preferably including an inductance coil, and an over-running clutch, are utilized in conjunction with any multi-speed generation system to alleviate impact on a utility grid during switching among operational speeds.

Wave motion electric generator

Abstract: Set out herein is an electrical generator conformed for installation in a buoy, the generator comprising an inverted pendulum having two windings formed at the free end thereof and aligned to articulate between two end stops each provided with a magnetic circuit As the loops thus pass through the magnetic circuit, electrical current is induced which may be rectified through a full way rectifier to charge up a storage battery The buoy itself may be ballasted to have its fundamental resonance at more than double the wave frequency with the result that during each passing of a wave at least two induction cycles occur

Rogowski coils: theory and experimental results

Abstract: The theory is given of the voltage output of a Rogowski coil excited by a current pulse flowing along the axis of the coil. In this theory the Rogowski coil is considered as a delay line. The results do not differ from those obtained usually by considering the coil as a voltage source dφ/dt with an inductive output impedance. Details are also given of the design of two Rogowski coils and their working modes are fully analyzed.

Audio-band electromechanical vibration converter

Abstract: Audio-band electromechanical vibration converter characterized in that a yoke having a magnetic pole and a magnetic gap formed therein is displaceably housed by a damper in a casing to which a vibration plate is attached; a coil attached to the casing is placed in said magnetic gap; and the casing gives an output of a mechanical vibration synchronized with a low-band audio-signal

Support structure for dynamoelectric machine stators spiral pancake winding

Abstract: A support structure for unitizing coil turns into a single member and bracing each coil of a multi-coil stator dynamoelectric machine Each stator coil includes several turns relatively concentrically disposed Each coil turn constitutes two longitudinal conductor portions and two end turn conductor portions One end turn portion serially connects two longitudinal portions and the remaining end turn portion serially connects one of the longitudinal portions with a longitudinal portion of a concentrically adjacent coil Each coil preferably lies in a plane defined by a portion of a cylinder and the coils are disposed in a cylindrical arrangement having a longitudinal axis therethrough such that one longitudinal portion of the outermost coil turn lies along the outer radial extent of the cylindrical arrangement and the remaining longitudinal portion of the outermost coil turn lies radially nearer the longitudinal axis of the cylindrical arrangement A rigid foundation member is situated in the plane of each coil within the concentrically innermost turn Turns of each coil are structurally connected either directly to the foundation member or indirectly to the foundation member by being intermediately joined to a turn already joined to the foundation member The concentric turns of each coil are separated by a predetermined distance through the use of interposed spacer members situated at desired axial and circumferential locations Such coils present a spiral pancake appearance and are cooperatively disposed in the cylindrical arrangement between radially inner and outer supporting structures Appropriately shaped wedges are disposed between selected coils and internal/external supporting members to account for the skewed or spiral manner in which each of the coils is arranged in the substantially cylindrical arrangement Radial tie rods extending between the radially internal and external support members structurally integrate those members so as to insure structural integrity of the cylindrical arrangement The radially external support member is preferably configured to extract load components from individual coil turns exposed at the cylindrical arrangement's outer periphery by either having radially inwardly directed struts extending between adjacent turns or having notches within which the radially outer conductor turns, when canted, are receivable

Flat electric coil with tap

Abstract: A miniaturized electric coil having a center tap which is constructed from a spiral-like bottom conductor pattern provided on a substrate, an insulating intermediate layer and a spiral-like top conductor pattern which is connected to the bottom conductor pattern via windows in the intermediate layer. A conductor path which is situated in the top conductor pattern is led out from the interior of the top conductor pattern to form the tap. At the area of said conductor path the conductors of the top conductor pattern are locally interrupted but are interconnected by means of said windows and connection conductors in the bottom conductor pattern that are connected parallel to the interruptions so as to ensure an undisturbed current flow in the top conductor pattern.

Molded end coil insulator

Abstract: A molded end coil insulator designed for attachment to a ferromagnetic core and which forms part of the ground insulation for magnet wires wound thereabout and about a series of pole pieces formed on the core. The end coil insulator includes features which improve the adaptability of the resulting device to automated winding of the magnet wires and connection of lead wires from an external circuit with the magnet wires. One such feature is an improved terminal support which receives and retains a terminal member in good electrical contact with a magnet wire, and which positively grips a lead wire from an external circuit in such a manner that a section of the lead wire connected with the terminal member is effectively isolated from strains and vibrations in the external circuit. Another feature of the molded end coil insulator is structure for positively restraining and guiding crossover sections of magnet wires which extend between the pole pieces. Still further features of the end coil insulator are its design for good heat transfer contact with the core, and its structure for retaining sheets of insulating material in openings in the core between the pole pieces.

Induction heating method for metal products

Abstract: A method of heating a long metal product to a desired temperature by an induction heating coil while continuously moving the long metal product longitudinally. The long metal product thus heated attains a uniform temperature throughout its entire length. For this purpose, the space enclosed by the induction heating coil is hypothetically divided into a plurality of sections in the direction in which the long metal product travels. The temperature of the long metal product in each hypothetically divided section is estimated by calculation from the temperature of the long metal product at the inlet of the induction heating coil. Based on the estimated temperatures, the power supplied to the induction heating coil is controlled so that the temperature of the long metal product agrees with the desired temperature at the outlet of the induction heating coil.

Digital eddy current apparatus for generating metallurgical signatures and monitoring metallurgical contents of an electrically conductive material

Abstract: The apparatus comprises a parallel coil and a capacitance, the coil having an air gap in which an unknown specimen is inserted, a source of alternating voltage applied to the coil-capacitance combination, scanning means for automatically varying the value of the capacitance in steps, thus varying the phase of the voltage across the coil, means for digitizing the phase of the voltage corresponding to each capacitance value, a memory in which those digitized phase values are stored, a reference memory containing digitized phase values for known specimens, and means for comparing the digitized phase values of the unknown specimen with those of known specimens. A digital tolerance control circuit is also provided which accommodates deviations between the reference and the known phase values, up to predetermined amounts, and means are provided for displaying the generic name or grade of the stored phase values which match the phase values of the unknown specimen.

Solenoid actuated valve device

Abstract: The solenoid actuated valve device is comprised of a housing of magnetic material having a radially disposed inlet and at least one axially disposed outlet in communication with the interior of a hollow magnetic core disposed within the body. An annular bobbin having a solenoid coil wound thereon is slidably mounted on the core and is normally biased into a position closing at least one elongated radially extending opening through the core. Permanent magnets are secured to the interior of the body in such a manner that the lines of flux intersect the solenoid coil at right angles thereto. Two springs normally bias the bobbin to the closed position and extend between one end of the bobbin and a spring support member disposed adjacent one end of the body. Each spring is connected to one end of the coil and to a respective electrical terminal for supplying electric current to the solenoid coil and the position of the spring support is adjustable relative to the end of the housing by means of a screw threadably extending through the end of the housing into engagement with the spring holder to vary the spring force acting on the bobbin. The connection between the two springs and the ends of the solenoid coil are insulated from the bobbin to prevent a short circuit which would deprive the solenoid coil of electric current. The connections between the two springs and the terminals are also encapsulated with insulating material subsequent to the adjustment of the spring holder relative to the end of the housing.

Brushless DC motor control utilizing a ROM

Abstract: The power switch driver circuit of a brushless DC motor control ensures synchronous operation by utilizing a ROM addressed by motor shaft position sensors. Excess current drawn by the motor windings is sensed by a detector which provides an additional bit of address input to correct the condition. The address input may also be modified by a bit signifying forward or reverse operation of the motor.

Electromagnetic flow meter

Abstract: PURPOSE:To measure the flow rate of fluid in high accuracy by providing difference between large and small energizing currents during ordinal value period and selecting the sampling interval for detecting both signal voltages at integer magnification of commerical power frequency. CONSTITUTION:An electromagnetic flow meter oscillator 4 consists of an exciting coil 5, a fluid flowing pipe 6 and electrodes 7, 7' and flows rectangular exciting current having two ordinal values at the coil 5 by a rectangular wave energizing circuit 1 to detect the difference between the signal voltage occurred at the larger ordinal exciting current and the signal voltage occurred at the smaller ordinal exciting current by a differential amplifier 12. It provides the difference between the period of the larger ordinal value of the exciting current and the period of the smaller ordinal value of the current and selects the interval from one sampling of the current to the other sampling thereof by a pulse generator 13 to the integer magnification of the period of commerical AC power supply so as to effectively remove the effects of the noise of the commerical power frequency and of electrochemical unbalance voltage.

Zero crossing detection and electronic compensation of D. C. saturation magnetization in current transformers used in watthour meter installations

Abstract: A watt hour meter installation is described which is of the type including an input transformer having an input winding for connection to an alternating current power supply line, an output winding for connection to a watt hour meter for measuring alternating current power being consumed and a bore on which the input and output windings are wound. The core is of the type which is susceptible to DC magnetization by a DC component superimposed on the alternating current being measured. In order to overcome the effect of the DC component on the magnetization characteristics of the input transformer, automatic compensation circuitry is provided which includes a sensor coupled to sense the current flowing through the input winding and for deriving a sensed output signal proportional to the sensed current and which includes both AC and DC components of the input current. A sensed signal processing circuit is provided in the form of positive and negative peak voltage detecting and holding circuit together with a summation circuit and voltage to current converter for deriving from the sensed signal a feedback signal which is proportional only to the DC component of the current flowing in the input winding. This feedback signal is supplied through a compensating winding wound on the input transformer core in a direction to automatically cancel out the effects of the superimposed DC component on the saturation characteristics of the input transformer.

Moving-coil linear motor

Abstract: A moving-coil linear motor suitable for driving a printer carriage of a serial printer is provided with a pair of coils disposed in side-by-side relationship. Logic circuitry is utilized to select which of the two coils should be energized, and in which direction current should flow through the coil in response to signals from a pair of magnetic field sensors mounted on the moving coil assembly.

Acoustic transducer of improved construction

Abstract: An improved transducer construction of the type having a U-shaped armature mounted to have a vibrating arm extending through the tunnel of a cooperating coil. The arms of the armature are joined by a smooth bend to provide improved shock-resistant characteristics. The coil is initially located and properly positioned relative to the arm extending through the tunnel by means of shims. The transducer includes a case comprising a cup, and a cover for the cup, both being of a magnetic material. The cup and cover are joined together by welding to insure low reluctance flux paths therebetween to retain the magnetic fields developed by the transducer within the casing.

Ignition device for internal combustion engine

Abstract: PURPOSE:To improve the ignition of an internal combustion engine, reduce the heat loss of an ignition coil and prevent a switch from burning, by connecting an inductive discharge type ignition circuit and a capacitive discharge type ignition ciricuit to a spark plug. CONSTITUTION:An inductive discharge type ignition circuit 10 as the first ignition ciricuit and a capacitive discharge type ignition circuit 40 as the second ignition circuit are connected to a spark plug 1. The first ignition circuit 10 acts to turn on and off the current of a primary coil 14a by opening and closing a contact 13 to cause a high-voltage current to flow through the secondary coil 14b. The second ignition circuit 40 acts to transmit electric charge stored in a capacitor 42 coupled to a primary coil 41a, to the primary coil to produce a high voltage across the secondary coil 41b.

The multicoil II airborne electromagnetic system

Abstract: A helicopter-towed electromagnetic (EM) system has been developed with two orthogonal transmitter coils. Units currently in service have either two or three orthogonal receiver coils. The associated software yields in-phase and quadrature channels which are generally free of the conductive response of overburden and of the magnetic induction response of magnetite. These geologic noise sources can mask the response of bedrock conductors for all previously developed airborne EM (AEM) systems. The new technique involves energizing conductors with two orthogonal transmitter coils, both operating at approximately the same frequency (e.g., 900 Hz). The subtracting of the secondary field components of one maximum-coupled coil pair from the other yields in-phase and quadrature difference channels. These channels may contain as much as an order-of-magnitude increase in the signal/noise (S/N) ratio for bedrock conductors in a geologically noisy environment.The new system can also indicate whether a steeply dipping conductor is thin (e.g., width less than 3 m) or thick (greater than 10 m). The thickness parameter provides a new criterion for conductor sorting, complementing the usual parameters of conductance and strike-length.The geophysical data are digitally recorded, and the profile records and maps are plotted by computer. The traces include the basic recorded data, the EM difference channels, a channel of resistivity, and a channel of conductance. The conductance channel essentially is an automatic anomaly selector calibrated in mhos.The usual application of the system is for metallic mineral prospecting. However, the system has also been used for sand and gravel detection using two well separated frequencies. For such applications, apparent resistivities are computed for each frequency and are displayed as channels on the profile record and as contour maps.

Auto resetting switchgear trip indicator circuits

Abstract: A trip indicator circuit for a circuit interrupter of an electric power system, which includes an electromagnetic status indicator, having an indicator which is movable between an indicating position and a non-indicating position, a pulse-actuated set coil for moving the indicator to the indicating position, and a pulse-actuated reset coil for moving the indicator to the non-indicating position. An indicator set circuit for energizing the set coil is connected across the trip coil by an electronic switching device which is rendered conductive by an overcurrent sensing circuit whenever a particular abnormal condition occurs in the electric power system, so that the set coil will be energized only when the circuit interrupter is tripped during the occurrence of the particular abnormal condition. A reset circuit is connected across the closing coil to energize the reset coil each time the circuit interrupter is closed. The reset circuit includes a capacitor which is connected across the closing coil in series with the reset coil and a first diode which is orientated so that, when the closing coil is energized, a current pulse flows through the first diode, the capacitor, and the reset coil until the capacitor is fully charged. The reset circuit further includes a resistor connected across the first diode, and a second diode connected across the reset coil and orientated to allow the capacitor to discharge through the resistor, the closing coil, and the second diode when the closing coil is deenergized. The resistor prevents two closely-spaced resetting operations of the indicator, which otherwise may occur when the interrupter is tripped immediately after being closed.

Winding apparatus and method

Abstract: An apparatus and method for winding continuous webs onto a core mandrel wherein the web is in contact with a rotating winding drum and is guided onto an empty core mandrel supported in a first operating position where winding is started and where a partially wound core mandrel is produced; the partially web-wound mandrel is transferred into a second operating position without interruption of coil formation when a predetermined coil of web has been formed; the web is cut by an automatic knife and the leading web edge produced is taken by another empty core mandrel supplied from a magazine into the first operating position; the fully wound coil is transferred from the second operating position to storage and the operating cycle is repeated; a force sensor is connected with the winding drum to measure the force that is exerted by the outer surface of the coil on the mandrel in the second operating position and a mechanical compensator is connected with the support that holds the mandrel in the second operating position; the output signal from the force sensor is fed into a control device that actuates the mechanical compensator to that the effective force exerted by the coil in the second operating position against the winding drum can be maintained at a predetermined value; and a drive is provided for central winding of the coil when in the second operating position.

Magnetic pickup for electric guitars

Abstract: A magnetic pickup for a stringed musical instrument, comprising a polar magnet having a polar axis extending across its thinnest dimension, a coil having a magnetically permeable pole piece extending upwardly for positioning adjacent an instrument string, with the polar magnet positioned longitudinally parallel to the coil and having its polar axis perpendicular to the winding axis of the coil. Positioned within the coil is either a magnet or a pole piece. The pickup may include a plurality of coils and magnets arranged as described above to increase the effectiveness of the pickup. Also disclosed is a method for manufacturing the pickup which includes setting the pole piece, coil, magnet, and mounting bracket in a mold cavity, and casting the entire unit with potting material.

Inductively heatable godet

Abstract: An improved means for mounting the induction coil of an inductively heated, rotatable godet about the magnetic core thereof so as to prevent internal overheating and preferably also to avoid any movement or play between the core and the coil as caused by heat expansion and vibration during operation of the godet. The improvement comprises cooling means for cooling the laminated pack acting as the magnetic core and for thermally isolating the pack from the coil and outer godet shell or casing, said cooling means including at least one hose-like tube wound around the laminated pack with means to conduct a fluid coolant therethrough. An elastic intermediate member is preferably introduced at some point between the coil and magnetic core in order to compensate for any unequal thermal expansion of these elements in the axial and/or radial directions.

30-MJ superconducting magnetic energy storage (SMES) unit for stabilizing an electric transmission system

Abstract: Electric power systems that have major loads and generation centers separated by large distances may experience low-frequency power oscillations. This type of oscillation has occurred on the Pacific AC Intertie that connects southern California and the Pacific Northwest. A separate, almost parallel, dc-transmission line also connects these areas. The Bonneville Power Administration, which operates this transmission system, has overcome the instability by controlling the power transmitted on the dc-transmission line. A 30-MJ (8.4-kWh) superconducting magnetic energy storage unit with a 10-MW converter could also provide damping for this instability. The conceptual design of the 30-MJ coil and the cryogenic and electrical components of the system are described. The system is to operate at a maximum current of 5 kA and will modulate the AC Intertie at 0.35 Hz. Discharge will be controlled to retain a minimum stored energy of 20 MJ to limit cyclic strains in the coil and ac losses in the conductor. The conductor will be made of multistrand-copper and copper-matrix, multifilament NbTi superconducting wires on a stainless steel mandrel.